Betweenness centrality is a measure used in network analysis to determine the importance of a node within a graph. It quantifies how often a node acts as a bridge along the shortest paths between other nodes. A higher betweenness centrality indicates that a node has more influence over the flow of information or resources in the network. This concept is particularly useful in various fields, such as social network analysis, transportation networks, and communication networks. By identifying key nodes with high betweenness centrality, researchers can better understand the structure and dynamics of complex systems.